Methods and apparatus for an osteotomy fixation or arthrodesis cage

ABSTRACT

A method and apparatus for an osteotomy fixation or arthrodesis cage allows the adjustment of the relative position of two bone segments while supporting the joining of those bone segments into one structure through the implant and methods described herein. The implant&#39;s embodiments fixate to the adjacent bones while inter-positioning its body between the bone segments. This inter-positioning allows anatomical adjustments in the distance between and angle of the bone segments. The adjustment is further enhanced by the use of shape memory materials that when activated through the application of heat energy, transition from a second shape to a first shape while changing the distance between the bones or their relative angle. This method and apparatus can be used on any adjacent bone or bone segments including but not limited to the vertebrae of the spine or long bone such as the tibia or metatarsal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to bone fixation devices for thestabilization, orientation and fusion of diseased joints (arthrodesis)or surgical cuts in bone (osteotomies).

2. Description of the Related Art

Repair of bone fractures, osteotomies, or the joining of two bone acrossa joint are long practiced medical techniques. Often these repairs canbe facilitated by immobilization with a splint or cast but often requiresurgical exposure of the bone and fixation with biocompatible implantsdesigned to reduce (bring together) and hold two or more bonystructures.

Wire fixation wires, pins, screws, staples, plates and rods have a longhistory of use. In spite of these technologies healing sometimes doesnot occur and the anatomy of the healed bone is often abnormal. Theprior art is replete with examples of devices that hold the bonestogether, but is more limited in references to those devices thatpresent a goal of achieving anatomical adjustments.

In the prior art, U.S. Pat. No. 6,127,597 to Beyar describes systems forthe percutaneous bone and spinal stabilization, fixation and repairthrough using devices that are placed in the medullary cavity of boneand expanded to engage and hold the bone segments. Described are selfexpanding implants, implants expandable by external power, and solidphase formation devices that expand. Though some of the embodimentsutilize shape memory metals such as nitinol as the mechanism forexpansion all suffer from a limited ability to provide fixation to thebone segments or anatomical correction.

U.S. Pat. No. 6,773,437 B2 describes a shape memory metal fixationstaple and method for correcting deformities of the growing adolescentbut does not correct the patient's anatomy through the use of theimplant, but restricts the growth of a portion of the spine so that thedeformity is corrected over years as the child grows. Once thecorrection is achieved, the implants are removed. This fixation implantthat has an anatomical goal suffers from the delay in the correction andthe removal of the implant. The implant alone does not achieve theanatomical correction, the growth of the skeleton does.

Implants that provide fixation and anatomical correction of the spineare described in U.S. Pat. Nos. 6,264,656 B1, 6,923,830 B2 and 7,003,394B2 by Michelson; U.S. Pat. No. 6,743,255 B2 by Ferree and U.S. Pat. No.6,656,178 B1 by Veldhuizen, and there are several that expand U.S. Pat.No. 6,488,710 by Besselink, U.S. Pat. No. 6,835,206 B2 by Jackson, andU.S. Pat. No. 7,018,415 B1 by McKay, but are all limited in use by thestatic nature of their anatomical correction, fixation elements that areseparate components or fixation elements that are limited in theirfixation ability, such as grooves, slots, ridges or external threads.Though these devices have fixation features and an anatomical formfactor they have a history of failure due to the poor fixation abilityof external threads, slots and rough surfaces and are limited by theirform so as to fit the anatomy versus effect the anatomy.

The subject invention overcomes the history or poor fixation with thesetypes of devices and allows the surgeon to effect the anatomy andrelative position of the bone segments by actively changing the implantshape in the spinal disk space or space between bone created with anosteotomy or resection of a joint.

SUMMARY OF THE INVENTION

In accordance with the present invention, bone fixation devices for thestabilization, orientation and fusion of diseased joints (arthrodesis)or surgical cuts in bone (osteotomies) are placed into a bony site tostabilize two adjacent bone segments. These segments could have normalanatomical features such as vertebra of the spine or separated throughsurgical cuts that subsequently require rejoining.

It is therefore an object of the present invention to join bone segmentswhile allowing the surgeon to control the distance between the segmentsand the relative orientation of those segments while providing a methodof fixation of those segments to one another.

It is a further object of the present invention to allow the surgeon,through the setting of the shape changing temperature of the materialused to make the implant and control of the heat applied to the implant,to adjust the orientation, separation and fixation forces applied to thebone segments by the implant.

Still other objects, features, and advantages of the present inventionwill become evident to those of ordinary skill in the art in light ofthe following. Also, it should be understood that the scope of thisinvention is intended to be broad, and any combination of any subset ofthe features, elements, or steps described herein is part of theintended scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A provides a perspective view of an inter-vertebral cage accordingto a first embodiment.

FIG. 1B provides a front view of the inter-vertebral cage in a firstshape according to the first embodiment.

FIG. 1C provides a front view of the inter-vertebral cage in the firstshape according to the first embodiment.

FIG. 2A provides a perspective view of the inter-vertebral cage in asecond shape according to the first embodiment.

FIG. 2B provides a front view of the inter-vertebral cage in the secondshape according to the first embodiment.

FIG. 3 provides a flowchart illustrating the method steps for utilizingthe inter-vertebral cage according to the first embodiment.

FIG. 4A provides a partial section view of the inter-vertebral cage inthe second shape according to the first embodiment.

FIG. 4B provides a partial section view of the inter-vertebral cage inthe first shape in an installed position according to the firstembodiment.

FIG. 5 provides a flowchart illustrating the method steps for utilizingthe inter-vertebral cage according to an extension of the firstembodiment.

FIG. 6A provides a perspective view of an inter-vertebral cage accordingto an extension of the first embodiment.

FIG. 6B provides a front view of the inter-vertebral cage in a firstshape according to the extension of the first embodiment.

FIG. 6C provides a front view of the inter-vertebral cage in the firstshape according to an extension of the first embodiment.

FIG. 7A provides a perspective view of the inter-vertebral cage in asecond shape according to an extension of the first embodiment.

FIG. 7B provides a front view of the inter-vertebral cage in the secondshape according to an extension of the first embodiment.

FIG. 8A provides a perspective view of an inter-vertebral cage in afirst shape according to a second embodiment.

FIG. 8B provides a front view of the inter-vertebral cage in the firstshape according to the second embodiment.

FIG. 8C provides a front view of the inter-vertebral cage in the firstshape according to the second embodiment.

FIG. 9A provides a perspective view of the inter-vertebral cage in asecond shape according to the second embodiment.

FIG. 9B provides a front view of the inter-vertebral cage in the secondshape according to the second embodiment.

FIG. 10 provides a flowchart illustrating the method steps for utilizingthe inter-vertebral cage according to the second embodiment.

FIG. 11A provides a partial section view of the inter-vertebral cage ina second shape according to the second embodiment.

FIG. 11B provides a partial section view of the inter-vertebral cage ina first shape in an installed position according to the secondembodiment.

FIG. 12A provides a perspective view of an inter-vertebral cage in afirst shape according to an extension of the second embodiment.

FIG. 12B provides a front view of the inter-vertebral cage in the firstshape according to the extension of the second embodiment.

FIG. 12C provides a front view of the inter-vertebral cage in the firstshape according to the extension of the second embodiment.

FIG. 13A provides perspective view of the inter-vertebral cage in asecond shape according to the extension of the second embodiment.

FIG. 13B provides a front view of the inter-vertebral cage in the secondshape according to the extension of the second embodiment.

FIG. 14 provides a method flowchart illustrating the method steps forutilizing the inter-vertebral cage according to the extension of thesecond embodiment.

FIG. 15A provides a partial section view of the inter-vertebral cage ina second shape before contraction according to the second embodiment.

FIG. 15B provides a partial section view of the inter-vertebral cage ina first shape after contraction according to the second embodiment.

FIG. 16A provides perspective view of the inter-vertebral cage accordingto a third embodiment.

FIG. 16B provides a front view of the inter-vertebral cage in a firstshape according to the third embodiment.

FIG. 17A provides a front view of the inter-vertebral cage in it'ssecond shape in a representation of an improperly curved spine accordingto the third embodiment.

FIG. 17B provides a front view of the inter-vertebral cage in it's firstshape where it assumes an expanded position to provide proper curvedspine alignment according to the third embodiment.

FIG. 18 provides a method flowchart illustrating the method steps forutilizing the inter-vertebral cage to angularly adjust vertebraeaccording to the third embodiment.

FIG. 19A provides a front view of an inter-vertebral cage in a secondshape including a separate closeout according to an extension of thethird embodiment.

FIG. 19B provides a front view of an inter-vertebral cage in a firstshape in an installed position before installation of the separatecloseout in a second shape according to the extension of the thirdembodiment.

FIG. 19C provides a front view of the inter-vertebral cage in a firstshape with the installed separate closeout in a first shape according tothe extension of the third embodiment.

FIG. 20 provides a flowchart illustrating the method steps for utilizingthe inter-vertebral cage according to the extension of the thirdembodiment.

FIG. 21A provides a section view of a cage in a second shape utilized ina tibia end portion adjustment operation according to a fourthembodiment.

FIG. 21B provides a section view of a cage in a first shape utilized ina tibia end portion adjustment operation according to the fourthembodiment.

FIG. 22 provides a flowchart illustrating the method steps for utilizingthe cage according to the fourth embodiment.

FIG. 23A provides a front view of a cage having a spacing member and acloseout disposed on an inner faces of the engagement plates accordingto a fifth embodiment.

FIG. 23B provides a perspective view of the cage having a spacing memberand a closeout disposed on an inner faces of the engagement platesaccording to the fifth embodiment.

FIG. 23C provides a front view of a spacing member having “Z” shapedexpansion members according to the fifth embodiment.

FIG. 23D provides a front view of a spacing member having interlacedexpansion members according to the fifth embodiment.

FIG. 23E provides a front view of a spacing member having “C” shapedexpansion members according to the fifth embodiment.

FIG. 23F provides a front view of a spacing member having “O” shapedexpansion members according to the fifth embodiment.

FIG. 23G provides a front view of a spacing member having interlacedexpansion members according to the fifth embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention, which may be embodied in variousforms. It is further to be understood that the figures are notnecessarily to scale, and some features may be exaggerated to showdetails of particular components or steps.

As illustrated in FIGS. 1A-2B, an inter-vertebral cage 100 may beconstructed from virtually any alloy exhibiting a shape-memory effect.Examples of shape-memory effect materials include, but are not limitedto nitinol, AuCd, FePt₃, beta Brass, and InTI. Shape memory effectmaterials allow an object to be: formed in an original shape; deformedwhile cooled to a martensitic state; then heated to a point where thedeformed object phase changes from the martensitic state to anaustenitic state, thereby returning the deformed object to its originalshape; and when it cools it retains this original shape or first shape.Accordingly, the inter-vertebral cage 100 is formed in an original orfirst shape 127 (FIGS. 1A-1C), and annealed to set its original shape.The inter-vertebral cage 100, while cold and in its martensitic phase,is then deformed to a second shape 128 (FIGS. 2A-2B). Next, theinter-vertebral cage 100 is heated until it phase changes to anaustenitic phase, thereby returning from the deformed or second shape128 to the original or first shape 127. Finally, the inter-vertebralcage 100 cools whereby the inter-vertebral cage 100 retains the originalfirst shape 127.

While this embodiment has been shown with the inter-vertebral cage 100moving from the second shape 128 to the first shape 127, it should beapparent that the inter-vertebral cage 100 is usable at virtually anypoint along the transition between the second shape 128 and the firstshape 127. Accordingly, an end-use shape may designate any shape betweenthe second shape 128 and up to and including the first shape 127. Theamount of heat energy applied to the deformed shape determines theamount of transition from the second shape 128 to the first shape 127.

The inter-vertebral cage 100 is utilized as a structural component forfixating two vertebrae together in cases where a disc is removed frombetween the two vertebrae. As shown in FIG. 1A, the inter-vertebral cage100 includes a body 104 having a first engagement plate 102, a secondengagement plate 103, and a spacing member 101 disposed between thefirst and second engagement plates 102 and 103. The spacing member 101includes a planar section 109 disposed between a bend 137 and a bend138. The first engagement plate 102 includes a first end 118 incommunication with a first end 125 of the spacing member 101, and asecond end 119 in communication with a first stop 115. The secondengagement plate 103 includes a first end 121 that is in communicationwith a second end 126 of the spacing member 101, and a second end 122that is in communication with a second stop 116. The first and secondstops 115 and 116 are substantially planar in shape with curvature asappropriate to match the bone anatomy, and extends as a continuous orinterrupted section across the entire length of the second ends 119 and122 of the first and second engagement plates 102 and 103. Theinter-vertebral cage 100 further includes a first leg 106 extending froma central point of the first stop 115, and a second leg 107 extendingfrom a central point of the second stop 116. While this embodiment hasbeen shown with planar stops 115 an 116, one of ordinary skill in theart will recognize that the size and shape of the stops 115 and 116 maybe altered to adapt to anatomy or varying attachment conditions, andthat virtually any amount of protrusion from the engagement plates maybe considered a stop.

For the purpose of clarity and to provide reference points, a horizontalaxis 190 and a vertical axis 191 have been provided in FIG. 1B. One ofordinary skill in the art will recognize that references to horizontaland vertical directions are complementary to the cited axes 190 and 191.It should further be understood that a vertical plane is defined as aplane passing through the vertical axis 191 and the horizontal axis 190,and a horizontal plane passes through the horizontal axis 190 and isperpendicular to the vertical plane. Additionally, the term “elevation”is utilized in reference to vertical displacement, wherein a lowerelevation is recognized below the horizontal axis 190 and a higherelevation is recognized above the horizontal axis 190. As such, anobject may move from a given elevation to a higher or lower elevation.

The inter-vertebral cage 100 further includes a bend 135 disposedbetween the first leg 106 and the first stop 115, and a bend 136disposed between the first stop 115 and the first engagement plate 102.The inter-vertebral cage 100 still further includes a bend 139 disposedbetween the second engagement plate 103 and the second stop 116, and abend 140 disposed between the second stop 116 and the second leg 107.One of ordinary skill in the art will recognize that the sizes of thebends 135-136 and 139-140, and the ranges of the bends 135-136 and139-140 may be adjusted to increase or decrease the span of theinter-vertebral cage 100.

The first engagement plate 102 is substantially planar, and includes afirst aperture 110. The second engagement plate 103 is substantiallyplanar, and includes a second aperture 111. The first and secondapertures 110 and 111 can be round or rectangular in shape, one ormultiple, and consuming slightly less than the area of an engagementplate 102 or 103, such that the apertures 110 and 111 are substantiallycentrally located within the first and second engagement plates 102 and103. In this example, the first and second engagement plates 102 and 103are disposed symmetrically about the spacing member 101. While thisembodiment has been shown with a spacing member 101 in contact withsymmetrical engagement plates 102-103, one of ordinary skill in the artwill recognize that the shape, length, and width of the spacing member101 and the engagement plates 102-103 may be changed to provideincreased height, load capability, an increased aperture size, differentlocation on the engagement plates 102-103, or a different geometry.Illustratively, the spacing member 101 may be located differently withrespect to the engagement plates 102-103, and does not have to span theentire length of the plates 102-103. Further, the spacing member 101 maybe broken up into multiple spacing members 101.

The inter-vertebral cage 100 further includes engagement areas 143 and144, as shown in FIG. 1B. Engagement area 143 includes a firstengagement surface 145, a second engagement surface 146, and a thirdengagement surface 147. The first engagement surface 145 is disposed onan outer surface of the first engagement plate 102, the secondengagement surface 146 is disposed on a side of the first stop 115nearest the spacing member 101, and the third engagement surface 147 isdisposed on a face of the first leg 106 that is nearest the firstengagement surface 145, such that an object between the first engagementsurface 145 and the third engagement surface 147 is compressed whenmoving from the second shape to the first shape, and contacts the secondengagement surface 146. Similarly, the second engagement area 144includes a first engagement surface 148, a second engagement surface149, and a third engagement surface 150. The first engagement surface148 is disposed on an outer surface of the second engagement plate 103,the second engagement surface 149 is disposed on a face of the secondstop 116 that lies nearest the spacing member 101, and the thirdengagement surface 150 is disposed on an inner face of the second leg107, such that the third engagement surface 150 is disposed oppositefrom the first engagement surface 148, and material between the firstand third engagement surfaces 148 and 150 is compressed while in contactor close proximity with the second engagement surface 149. While thefirst and second engagement areas 143-144 have been shown with threeengagement surfaces, one of ordinary skill in the art will recognizethat the number and locations of the engagement surfaces may vary,depending on the specific configuration, number of legs, and in vivoconditions.

The inter-vertebral cage 100 further includes a closeout 105 thatextends from an inner surface of the first engagement plate 102. In thisembodiment, the closeout 105 spans the entire length of the firstengagement plate 102, and extends toward the second engagement plate103, such that a cavity 108 is created between the spacing member 101,the first engagement plate 102, the second engagement plate 103, and thecloseout 105. While the closeout 105 has been shown as protruding fromthe first engagement plate 102, one of ordinary skill in the art willrecognize that the closeout may extend from other surfaces, and that thecloseout 105 may be broken into multiple segments.

The inter-vertebral cage 100 may further include at least one barb 113disposed on the first engagement surface 145 and the first engagementsurface 148. The barbs 113 are oriented such that they restrict themovement of the inter-vertebral cage 100 out of an installed position.One of ordinary skill in the art will recognize that additional barbs113 may be added to the engagement surface or leg, and utilized toprovide increased resistance, and that the sizes of the barbs 113 may beadjusted as necessary to ensure adequate resistance.

In the first shape 127, as shown in FIGS. 1A-1C, the first engagementplate 102 and the spacing member 101 are disposed at an angle 162, andthe second engagement plate 103 is disposed at an angle 163 relative tothe spacing member 101. In this example, the first engagement plate 102and the second engagement plate 103 are disposed substantiallyperpendicular to the spacing member 101 and in proximity to each other,such that the first engagement plate 102 and the second engagement plate103 are substantially symmetrical about the spacing member 101, and acavity 108 is created between the first engagement plate 102 and thesecond engagement plate 103. While the first and second engagementplates 102 and 103 have been shown as being substantially perpendicularto the spacing member 101, one of ordinary skill in the art willrecognize that the angles 162 and 163 may be adjusted to adapt tolocation specific features, or varying angles of correction.

The first stop 115 is disposed at an angle 161 relative to the firstengagement plate 102. In this example of the first shape 127, the firststop 115 is disposed substantially perpendicular relative to the firstengagement plate 102, and extends away from the second engagement plate103. Similarly, the second stop 116 is disposed at an angle 164 relativeto the second engagement plate 103. In this first shape 127, the secondstop 116 is disposed substantially perpendicular to the secondengagement plate 103, and extends away from the first engagement plate102. The first leg 106 is disposed at an angle 160 relative to the firststop 115, and extends downward towards the spacing member 101. In thisfirst shape 127, the angle 160 is approximately sixty degrees. However,one of ordinary skill in the art will recognize that the specific anglesof this embodiment may be adjusted to overcome irregular implant siteconditions. Similarly, the second leg 107 is disposed at an angle 165relative to the second stop 116, and also extends towards the spacingmember 101. In this first shape 127, the angle 165 is substantiallyidentical to the angle 160, such that the legs 106 and 107 aresymmetrical, and apply an evenly distributed load. Additionally, thecloseout 105 is substantially planar and is disposed at an angle 166relative to the first engagement plate 102. In this first shape 127, theangle 166 is substantially ninety degrees, such that the closeout 105contacts the second engagement plate 103, thereby transferring loadsfrom the first engagement plate 102 to the second engagement plate 103,and from the second engagement plate 103 to the first engagement plate102. While this embodiment has been shown with a substantially planarcloseout 105 disposed at an angle of approximately ninety degrees, oneof ordinary skill in the art will recognize that the closeout 105 may beof virtually any shape that provides a closing out function. It shouldfurther be understood that the closeout may be disposed at virtually anyangle that maintains a stand off from the attaching engagement plate.

In the second shape 128, the inter-vertebral cage 100 is deformed asshown in FIGS. 2A-2B, such that the bends 137 and 138 of the first shape127 are extended to obtuse angles 172 and 173. Accordingly, in thesecond shape 128, the first engagement plate 102 is disposed at an angleof one hundred and ten degrees relative to the spacing member 101, andthe second engagement plate 103 is likewise disposed at an angle of onehundred and ten degrees relative to the spacing member 101. The bends136 and 139 are similarly contracted from their positions in the firstshape 127 to angles 171 and 174, thereby slightly rotating the first andsecond stops 115 and 116 towards the spacing member 101. Similarly, thebends 135 and 140 are extended to angles 170 and 175, such that thefirst and second legs 106 and 107 are disposed at an angle ofapproximately one hundred and ten degrees relative to their respectivestops 115 or 116. Additionally, the closeout 105 is deformed towards thespacing member 101, thereby contracting angle 166 to an angle 176. Inthis second shape 128, the closeout 105 is disposed at an angle ofapproximately seventy-five degrees relative to the first engagementplate 102. In this position, the first leg 106 and the second leg 107are disposed substantially parallel to each other, such that the legs106 and 107 may be inserted into bones simultaneously. While theengagement plates 102-103 and legs 106-107 have been shown at particularangles relative to the spacing member 101, one of ordinary skill in theart will recognize that other angles are possible, and should be viewedas part of this invention. It should further be recognized that the useof the parallel legs 106 and 107 is conducive to the impaction of thelegs 106 and 107 into vertebra or the insertion of the legs 106 and 107into pre-drilled holes; however, other angles may be utilized to addressalternative situations, including the insertion of one leg at a time.

Upon the application of energy, the inter-vertebral cage 100 in thedeformed or second shape 128 (deformed martensitic phase), commences tochange from the martensitic state to the austenitic state. Uponcompletion of the austenitic phase change, the inter-vertebral cage 100has returned to the original or first shape 127. Upon cooling, theinter-vertebral cage 100 retains the original or first shape 127. One ofordinary skill in the art will recognize that upon the transformation ofa shape memory alloy to the original shape 127, a force is created, andaccordingly, the inter-vertebral cage 100 may be utilized inapplications where retaining and residual forces are required.

In this first embodiment, the phase change from the deformed or secondshape 128 to the original or first shape 127 creates forces as shown inFIG. 1C. The bend 135 moves from the angle 170 (obtuse angle associatedwith second shape 128) to a more acute angle 160 (acute angle associatedwith the first shape 127), thereby rotating the first leg 106 toward thefirst engagement plate 102. In a similar fashion, the bend 140 movesfrom the angle 175 (obtuse angle associated with second shape 128) to amore acute angle 165 (acute angle associated with the first shape 127),thereby rotating the second leg 107 towards the second engagement plate103. The bend 136 moves from the angle 171 (obtuse angle associated withsecond shape 128) to a smaller angle 161 (associated with the firstshape 127). Similarly, the bend 139 moves from the angle 174 (obtuseangle associated with second shape 128) to a smaller angle 164(associated with the first shape 127). Additionally, the bend 137 movesfrom angle 172 (obtuse angle associated with second shape 128) to angle162 (smaller angle associated with first shape 127). Similarly, the bend138 moves from the angle 173 (obtuse angle associated with second shape128) to angle 163 (smaller angle associated with first shape 127).Further, the closeout 105 moves from angle 176 (acute angle associatedwith second shape 128) to the angle 166 (larger angle associated withfirst shape 127).

In this first embodiment, compressive forces are created between thefirst engagement surface 145 and the third engagement surface 147.Additionally, compressive forces may be created between the secondengagement surface 146 and the third engagement surface 147 as the firstleg 106 closes down on material disposed between the first leg 106 andthe first engagement plate 102. Compressive forces are also createdbetween the third engagement surface 150 and the first engagementsurface 148, and between the third engagement surface 150 and the secondengagement surface 149 as the second leg 107 moves towards the secondengagement plate 103. Compressive forces are further created between thefirst engagement plate 102 and the second engagement plate 103 as thebends 137-138 contract to angles 162 and 163, respectively. When thefirst and second legs 106 and 107 are secured, a thrust force componentis created as the inter-vertebral cage 100 moves from the first shape127 to the second shape 128. The thrust force, shown in FIG. 1C, liesperpendicular to the plane of the spacing member 101 and away from athird engagement area 151. The thrust force is created when the legs 106and 107 are pinned, and the first and second engagement plates 102 and103 move towards each other during the shape change.

FIG. 3 provides a flowchart illustrating the method steps associatedwith utilizing the inter-vertebral cage 100 to fuse two vertebraetogether. The process commences with step 10, wherein a surgeon fixatesa first vertebra 180 and a second vertebra 181 at a desired workingposition. The surgeon continues with step 12, wherein a first locationis identified in the first vertebra 180, and a second location isidentified in the second vertebra 181 at a spacing complementary to aspacing between the legs 106 and 107 of the inter-vertebral cage 100.The process continues with step 14, wherein the surgeon inserts the legs106-107 into the first and second locations, such that the first andsecond engagement plates 102 and 103 are disposed between the first andsecond vertebrae 180 and 181. In step 16, the surgeon applies energy tothe first and second legs 106 and 107 of the inter-vertebral cage 100,thereby securing the inter-vertebral cage 100 to the first and secondvertebrae 180 and 181. The process continues with step 18, wherein thesurgeon applies energy to the body 104 of the inter-vertebral cage 100to move the first and second vertebrae 180 and 181 into a desiredcorrective position. Once the first and second vertebrae 180 and 181 arein the desired corrective position, the surgeon inserts bone graftmaterial into the cavity 108, such that the bone graft material uniteswith the first and second vertebrae 180 and 181 through the first andsecond apertures 110 and 111. Upon bone fusion, the graft material andthe first and second vertebrae 180 and 181 become a single unit.

FIG. 4A provides a side view of the inter-vertebral cage 100 in thesecond shape 128, wherein the first leg 106 and the second leg 107 aresubstantially parallel to each other, and the closeout 105 is angledslightly downward. Upon insertion of the first leg 106 into the firstlocation on the first vertebra 180, and the insertion of the second leg107 into the second location on the second vertebra 181, the body 104moves between the vertebrae 180 and 181, until the second engagementsurface 146 and the second engagement surface 149 contact the respectivevertebra 180 or 181. The barbs 113 engage the vertebrae 180 and 181,thereby securing the inter-vertebral cage 100 to the vertebrae 180 and181. Upon full insertion, the spacing member 101 and the engagementplates 102 and 103 are disposed between the vertebrae 180 and 181. Inthis position, the closeout 105 does not contact the second engagementplate 103. Upon the application of energy to the legs 106 and 107, thelegs 106 and 107 move from the second shape 128 to the first shape 127,thereby drawing the legs 106 and 107 toward the inter-vertebral cage100, and further securing the inter-vertebral cage 100 to the vertebrae180 and 181, as shown in FIG. 4B. Upon the application of energy to thebody 104, the closeout 105 moves from the second shape 128 to the firstshape 127, thereby extending towards the second engagement plate 103,and the bends 137 and 138 contract to the first shape 127, therebydrawing the second engagement plate 103 towards the first engagementplate 102, until the second engagement plate 103 contacts the newlyextended closeout 105. At this point, the cavity 108 is substantiallyclosed out, as shown in FIG. 4B. While this embodiment has been shownwith bone graft material being inserted after the application of energyto the body 104 of the inter-vertebral cage 100, one of ordinary skillin the art will recognize that bone graft material may be inserted intothe cavity 108 at alternate times, or not at all.

FIG. 5 provides a flowchart illustrating the method steps of the processdisclosed in FIG. 3 in an alternate order. In this extension of thisfirst embodiment, bone graft material may be inserted into the cavity108 before the application of energy to the body 104. The processcommences with step 22, wherein a surgeon fixates a first vertebra 180and a second vertebra 181 at a desired working position. The surgeoncontinues with step 24, wherein a first location is identified in thefirst vertebra 180, and a second location is identified in the secondvertebra 181 at a spacing complementary to a spacing between the legs106 and 107 of the inter-vertebral cage 100. The process continues withstep 26, wherein the surgeon inserts the inter-vertebral cage 100 intothe first and second locations, such that the body 104 is disposedbetween the first and second vertebrae 180 and 181. The surgeon theninserts bone graft material into the cavity 108 to promote fusion of thevertebrae 181 and 180, step 28. In step 30, the surgeon applies energyto the first and second legs 106 and 107 of the inter-vertebral cage100, thereby securing the inter-vertebral cage 100 to the first andsecond vertebrae 180 and 181. The process continues with step 32,wherein the surgeon applies energy to the body 104 of theinter-vertebral cage 100 to move the first and second vertebrae 180 and181 into a desired corrective position. While this extension of thefirst embodiment has been shown with the insertion of bone graftmaterial before the application of energy to the inter-vertebral cage100, one of ordinary skill in the art will recognize that a surgeon willadd bone graft material after moving the first and second vertebrae 180and 181 into the desired corrective position if an improper amount ofbone graft material remains in the cavity 108. Accordingly, thisextension of the first embodiment may include an additional step ofadding additional bone graft material after step 32. The bone graftmaterial unites with the first and second vertebrae 180 and 181 throughthe first and second apertures 110 and 111. Upon bone fusion, the graftmaterial and the first and second vertebrae 180 and 181 become a singleunit. One of ordinary skill in the art will further recognize thateither process may be employed to achieve similar results. While themethod of implanting inter-vertebral cage 100 has been presented, one ofordinary skill in the art will further recognize that the sequence ofsteps may be changed to meet a specific clinical need.

In an extension of the first embodiment, an inter-vertebral cage 192 issubstantially identical to the inter-vertebral cage 100, however theinter-vertebral cage 192 includes additional legs. Accordingly, likeparts have been referenced with like numerals. As shown in FIGS. 6A-6C,the inter-vertebral cage 192 includes a spacing member 101 attached tofirst and second engagement plates 102 and 103, and first and secondstops 115 and 116 disposed at the ends of the first and secondengagement plates 102 and 103. The inter-vertebral cage 192 furtherincludes a first leg 106, a second leg 107, a third leg 193, and afourth leg 194. The first leg 106 and the third leg 193 extend from thefirst stop 115 in a similar fashion to the inter-vertebral cage 100,however, the first and third legs 106 and 193 are disposed at extremeends of the first stop 115. Similarly, the second and fourth legs 107and 194 are disposed at extreme ends of the second stop 116. One ofordinary skill in the art will recognize that other embodiments thatinclude fewer or a greater number of legs are within the scope of thisinvention. Additionally, it should further be understood that whilethese legs are shown as being symmetrical, and balanced, it is possibleto provide an odd number of legs, as dictated by body conditions.

The inter-vertebral cage 192 is also formed from a shape memory alloy,and accordingly, also moves from a second shape 128 to a first shape127, or any point therebetween, in similar fashion to theinter-vertebral cage 100. FIGS. 6A and 6B provide illustrations of theinter-vertebral cage 192 in the first shape 127, and FIGS. 7A-7B providean illustration of the inter-vertebral cage 192 in a deformed or secondshape 128. Upon the transformation of the inter-vertebral cage 192 fromthe second shape 128 to the first shape 127, forces are created as shownin FIG. 6C. Operation of the inter-vertebral cage 192 is substantiallyidentical to the inter-vertebral cage 100, however in the case of theinter-vertebral cage 192, four legs are disposed within a first andsecond vertebrae, and energy must also be applied to the additional legs193 and 194. The surgeon must further identify a third location in thefirst vertebra 180, and a fourth location in the second vertebra 181, ata spacing complementary to the four legs 106, 107, 193, and 194 of theinter-vertebral cage 192. All other aspects of the inter-vertebral cage192 are obvious to one of ordinary skill in the art when compared to theinter-vertebral cage 100, and therefore, will not be further described.

In a second embodiment, an inter-vertebral cage 200 is similar infunction to the inter-vertebral cage 192, however the inter-vertebralcage 200 includes a vertebrae distraction function. The inter-vertebralcage 200 is similarly constructed from a shape memory alloy, andtherefore, may be returned to any point up to an original shape with theapplication of energy. As shown in FIGS. 8A-8B and 9A-9B, theinter-vertebral cage 200 includes a body 204 having a spacing member201, a first engagement plate 202, and a second engagement plate 203.The spacing member 201 includes an extension section 212, a bend 237,and a bend 238. The extension section 212, in a first shape 227,includes a width 211, and, in a second shape 228, a width 213.

The first engagement plate 202 includes a first end 217 in communicationwith a first end 231 of the spacing member 201, and a second end 218 incommunication with a first stop 215. The second engagement plate 203includes a first end 223 that is in communication with a second end 232of the spacing member 201, and a second end 224 that is in communicationwith a second stop 216. The first and second stops 215 and 216 aresubstantially planar in shape, and extend the entire length of thesecond ends 218 and 224 of the first and second engagement plates 202and 203. The first engagement plate 202 includes a first aperture 221substantially identical to that of the first embodiment, and the secondengagement plate 203 includes a second aperture 222 substantiallyidentical to that of the first embodiment.

This second embodiment includes a plurality of legs extending from thestops 215 and 216. Illustratively, in this particular example, a firstleg 206, a second leg 207, a third leg 208, and a fourth leg 209 areutilized for securing the inter-vertebral cage 200 to bones. In thissecond embodiment, the first leg 206 and the third leg 208 are disposedon extreme ends of the first stop 215, and the second and fourth legs207 and 209 are disposed on extreme ends of the second stop 216, insimilar fashion to the inter-vertebral cage 192. While this secondembodiment has been shown with the inter-vertebral cage 200 having fourlegs, one of ordinary skill in the art will recognize that fewer or morelegs may be utilized as necessary to adapt to in vivo conditions.

The inter-vertebral cage 200 includes a bend 235, a bend 236, a bend239, and a bend 240, as shown in the first embodiment. The bends 235through 240 move through a range of angles bordered by an original orfirst shape 227, and a deformed or second shape 228, in similar fashionto the first embodiment.

The inter-vertebral cage 200 further includes a closeout 205 attached tothe first engagement plate 202. In this embodiment, the closeout 205 isextended downward slightly in the second shape 228, and extends towardsthe second engagement plate 203 upon the application of energy. Uponfull extension of the closeout 205, and the contraction of the bends237-238, the closeout 205 is in contact with the second engagement plate203, thereby providing load bearing support between the first engagementplate 202 and the second engagement plate 203.

The extension section 212 provides the capability to increase the width213 associated with the second shape 228 to the width 211 associatedwith the first shape 227. In this second embodiment, the extensionsection 212 is a curvature formed into the shape memory material. Thecurvature flattens out upon the application of energy to the body 204.As such, the bend 237 and the bend 238 move away from each other. Theextension section 212 may be flattened out to any point along thetransformation from the deformed position to the original position, aspreviously disclosed. While this embodiment has been shown with a singleextension section 212, one of ordinary skill in the art will recognizethat multiple extension sections may be utilized to create increaseddisplacements. Additionally, the amount of displacement for a givenextension section may be altered by varying the radius, and or thicknessof the extension section, as well as its form.

In a second embodiment of the spacing member 201, the spacing member 201includes a third engagement surface 210 with “S” or “Z” shaped extensionmembers that run from bend 237 to 238. This member is deformed so thatit is a straight member in its first shape and “S” or “Z” shaped in itssecond shape. When placed into the bone and heated the extension memberchanges back to a straight member, and causes the extension section 212to increase in length from 213 to 211.

The feature of lengthening the spacing member 201 and adjusting thecloseout 205 allows the implant to be used to change the relative anglesand positions of the bones. Through partial heat activation of theextension section 212 the bone angle can be set.

FIG. 10 provides a method flowchart illustrating the steps associatedwith utilizing the inter-vertebral cage 200 to move a first and a secondvertebra 280 and 281 to a corrective position. The method shown in FIG.10 is similar to the method of FIG. 3. However, the method of FIG. 10provides the ability to separate and lift the first vertebra 280 fromthe second vertebra 281. As shown in step 50 of the method flowchart, asurgeon fixates a first vertebra 280 and a second vertebra 281 at adesired working position. The process continues with step 52, whereinthe surgeon must identify securing locations in the first and secondvertebrae 280-281, at a spacing complementary to leg spacings 206-209 ofthe inter-vertebral cage 200. Step 54 provides for inserting the legs206-209 of the inter-vertebral cage 200 into the securing locations,such that the engagement plates 202 and 203 and the spacing member 201of the inter-vertebral cage 200 are disposed between the vertebrae 280and 281. Upon insertion, the surgeon moves to step 56, wherein energy isapplied to the legs 206-209 of the inter-vertebral cage 200, therebysecuring the inter-vertebral cage 200 to the first and second vertebrae280 and 281. The process continues with step 58, wherein energy isapplied to the body 204 of the inter-vertebral cage 200, thereby movingthe first and second vertebrae 280 and 281 into a desired correctiveposition, locking the closeout 205, and further distracting the firstvertebra 280 and the second vertebra 281 by moving the extension feature212 from the width 213 to width 211. The surgeon may then insert bonegraft material into the cavity 219, thereby promoting the fusion of thefirst vertebra 280 and the second vertebra 281, step 60.

As shown in FIG. 11A, the legs 206-209 of a inter-vertebral cage 200, ina deformed position, are inserted into the first vertebra 280 and thesecond vertebra 281, such that the engagement surfaces 145 through 150,as described in the first embodiment, contact the first and secondvertebra 280 and 281. Upon full insertion, energy is applied to the legs206-209, such that the legs 206-209 move toward the engagement plates202-203, thereby securing the inter-vertebral cage 200 to the eachrespective vertebra 280 or 281. Upon the application of energy to thebody 204, the closeout 205 extends toward the second engagement plate203, and the bends 237 and 238 contract, thereby moving the engagementplates 202 and 203 closer together. When the second engagement plate 203contacts the closeout 205, the vertebrae 280 and 281 are aligned in thedesired corrective position, and the closeout 205 provides support inthe vertical direction. Upon further application of energy, theextendable feature 212 of the spacing member 201 flattens out to provideseparation between the first and second vertebra 280 and 281 and set thecurvature of the spinal vertebral bodies, as shown in FIG. 11B.

Once the first and second vertebrae 280 and 281 are in the desiredcorrective position, the surgeon inserts bone graft material into thecavity 219, such that the bone graft material unites with the first andsecond vertebrae 280 and 281 through the first and second apertures221-222. Upon bone fusion, the graft material and the first and secondvertebrae 280 and 281 become a single unit.

In an extension of the second embodiment, an inter-vertebral cage 250 issimilar in design to the inter-vertebral cage 200, however theinter-vertebral cage 250 includes a spacing member 251 providing acontraction function instead of an extension function, as shown in FIGS.12A-12C. Accordingly, like parts have been annotated with like numerals.The inter-vertebral cage 250 is similarly constructed from a shapememory alloy, and therefore, may be returned to any point up to anoriginal shape with the application of energy. The inter-vertebral cage250 includes a body 204 having a spacing member 251, a first engagementplate 202, and a second engagement plate 203. The spacing member 251includes a contraction section 252, a bend 237, and a bend 238. Thecontraction section 252, in a first shape 227, includes a width 253, an,in a second shape 228, as shown in FIGS. 13A-13B, a width 254. All otheraspects and components of the inter-vertebral cage 250 are identical tothose presented in the second embodiment, and therefore, will not befurther described.

The contraction section 252 provides the capability to decrease thewidth 254 associated with the second shape 227 to the width 253associated with the first shape 227. In this extension of the secondembodiment, the contraction section 252 is a curvature formed in theshape memory material. The curved portion constricts upon theapplication of energy to the body 204. As such the bends 237 and 238move toward each other. The contraction section 252 may be constrictedto any point along the transformation from the deformed position to theoriginal position, as previously disclosed. While this embodiment hasbeen shown with a single contraction section, one of ordinary skill inthe art will recognize that multiple contraction sections may beutilized to create increased contractions. One of ordinary skill in theart will further recognize that the inclusion of both a contractionsection 252 and an extension section 212 of the second embodiment in aspacing member is within the scope of this invention.

FIG. 14 provides a method flowchart illustrating the steps associatedwith utilizing the inter-vertebral cage 250 to move a first and a secondvertebra 280 and 281 to a corrective position. The method shown in FIG.14 is similar to the method of FIG. 10. However, the method of FIG. 14provides the ability to contract the first vertebra 280 and the secondvertebra 281. As shown in step 62 of the method flowchart, a surgeonfixates a first vertebra 280 and a second vertebra 281 at a desiredworking position. The process continues with step 64, wherein thesurgeon must identify securing locations in the first and secondvertebrae 280-281, at a spacing complementary to leg spacings 206-209 ofthe inter-vertebral cage 250. Step 66 provides for inserting the legs206-209 of the inter-vertebral cage 250 into the securing locations,such that the engagement plates 202 and 203 and the spacing member 251of the inter-vertebral cage 250 are disposed between the vertebrae 280and 281. Upon insertion, the surgeon moves to step 68, wherein energy isapplied to the legs 206-209 of the inter-vertebral cage 250, therebysecuring the inter-vertebral cage 250 to the first and second vertebrae280 and 281. The process continues with step 70, wherein energy isapplied to the body 204 of the inter-vertebral cage 250, thereby movingthe first and second vertebrae 280 and 281 into a desired correctiveposition, and further contracting the first vertebra 280 and the secondvertebra 281 by constricting the contraction section 252 from the width254 to width 253. The surgeon may then insert bone graft material intothe cavity 219, thereby promoting the fusion of the first vertebra 280and the second vertebra 281, step 72. While the method of implantinginter-vertebral cage 250 has been presented, one of ordinary skill inthe art will recognize that the sequence of steps may be changed to meeta specific clinical need.

Upon the application of energy to the body 204 and legs 206-209 of theinter-vertebral cage 250, forces are generated as shown in FIG. 12C. Asthe legs 206-209 move closer to the first and second engagement plates202-203, compressive forces are created between the legs 206-209 and theengagement plates 202-203. Compressive forces are created between thefirst and second engagement plates 202-203 when the engagement platesmove together. Additionally, compressive forces are created between thefirst and second engagement plates 202 and 203 when the contractionsection 252 constricts.

As shown in FIG. 15A, the legs 206-209 of a inter-vertebral cage 250, ina deformed position, are inserted into the first vertebra 280 and thesecond vertebra 281, such that the engagement surfaces 145 through 150,as described in the first embodiment, contact the first and secondvertebra 280 and 281. Upon full insertion, energy is applied to the legs206-209, such that the legs 206-209 move toward the engagement plates202-203, thereby securing the inter-vertebral cage 250 to the eachrespective vertebra 280 or 281, as shown in FIG. 15B. Upon theapplication of energy to the body 204, the closeout 205 extends towardthe second engagement plate 203, and the bends 237 and 238 contract,thereby moving the engagement plates 202 and 203 closer together. Whenthe second engagement plate 203 contacts the closeout 205, the vertebrae280 and 281 are aligned in the desired corrective position, and thecloseout 205 provides support in the vertical direction. Upon furtherapplication of energy, the contraction section 252 of the spacing member251 constricts to bring the first and second vertebra 280 and 281 closertogether, as shown in FIG. 15B.

Once the first and second vertebrae 280 and 281 are in the desiredcorrective position, the surgeon inserts bone graft material into thecavity 219, such that the bone graft material unites with the first andsecond vertebrae 280 and 281 through the first and second apertures221-222. Upon bone fusion, the graft material and the first and secondvertebrae 280 and 281 become a single unit.

In a third embodiment, an inter-vertebral cage 300, as shown in FIGS.16A-16B, is similarly constructed from shape memory material, and, insimilar fashion to the first and second embodiments, may move from asecond shape 328 to a first shape 327. It should be apparent that theinter-vertebral cage 300 is usable at virtually any point along thetransition between the second shape 328 and the first shape 327, asshown in FIGS. 17A-17B. Accordingly, an end-use shape may designate anyshape between the second shape 328 and up to and including the firstshape 327. The amount of heat energy applied to the deformed shapedetermines the amount of transition from the second shape 328 to thefirst shape 327.

As shown in FIGS. 16A-16B, the inter-vertebral cage 300 includes aspacing member 301 disposed between a first engagement plate 302 and asecond engagement plate 303. The spacing member 301 includes a planarsection 312 disposed between a bend 337 and a bend 338. Theinter-vertebral cage 300 further includes a closeout 305 extending fromthe first engagement plate 302, and legs 306 through 309 disposed on theengagement plates 302 and 303 in similar fashion to the inter-vertebralcage 192. The engagement plates 302 and 303 further include a first end318 and a second end 319, wherein stops 320 and 321 are disposed on thesecond ends 319 of the engagement plates 302 and 303. The engagementplates 302 and 303 further include apertures 310 and 311 to aid in bonegrafting operations. The inter-vertebral cage 300 further includes bends335-336 and 339-340, and first through third engagement surfaces345-350, in similar fashion to the previous embodiments.

In the first shape 327, the second ends of the engagement plates 302 and303 are disposed at a maximum angle relative to each other, therebycreating a width 315 between the second ends 319 of the engagementplates 302 and 303, as shown in FIG. 17B. In this specific example, theengagement plates 302 is disposed at an angle 362 relative to the planarsection 312 of the spacing member 301, and engagement plate 303 isdisposed at an angle 363 relative to the planar section 312. In thisspecific example, each engagement plate 302-303 is disposed at an angleof approximately one hundred and ten degrees relative to the planarsection 312 of the inter-vertebral cage 300. While one hundred and tendegrees has been shown, one of ordinary skill in the art will recognizethat virtually any angle may be utilized. In similar fashion to thepreviously disclosed embodiments, the legs 306 through 309 contracttowards their respective engagement plates 302 or 303. In this firstshape 327, the legs 306-309 are disposed at angle 360 and 365 relativeto the stops 320 and 321, and the stops 320 and 321 are disposed atangle 361 and 364 relative to the engagement plates 302 and 303. In thisspecific example of the first shape 327, the legs 306 through 309 aredisposed at an angle of approximately eighty degrees relative to theplanar section 312 of the spacing member 301. One of ordinary skill inthe art will recognize that this invention is not limited the legs beingdisposed at approximately eighty degrees relative to the planar section312.

Additionally, the closeout 305 extends toward the second engagementplate 303 until it contacts the second engagement plate 303. In thisexample of the first shape 327, the closeout 305 is disposed at an angle366. Specifically, the closeout 305 is disposed substantially parallelto the planar section 312 of the spacing member 301. While the closeouthas been shown as being substantially parallel to the planar section 312of the spacing member 301, one of ordinary skill in the art willrecognize that other angles are possible, and should be construed aspart of this invention.

In the second shape 328, the inter-vertebral cage 300 is deformed asshown in FIG. 17A, such that bends 337 and 338 of the first shape 327are contracted to angles 372 and 373, respectively. In this specificexample of the second shape 328, the engagement plates 302 and 303 aredisposed at an angle of ninety degrees relative to the planar section312 of the spacing member 301. However, one of ordinary skill in the artwill recognize that any angle from the second shape 328 up to anincluding the first shape 327 may be utilized as an end use shape. Thebends 335-336 and 339-340 are similarly extended from their positionsassociated with the first shape 327. In this second shape, the legs306-309 are disposed at an angle 370 and 375 relative to the stops 320and 321. The stops 320 and 321 are disposed at angle 371 and 374, suchthat the legs 306-309 are disposed substantially perpendicular to theplanar section 312 of the spacing member 301, and substantially parallelto each other. In this specific example, the legs are disposed at anangle of substantially ninety degrees relative to the stops 320 and 321,and the stops 320 and 321 are disposed at an angle of substantiallyninety degrees relative to the engagement plates 302 and 303. Whilesubstantially perpendicular angles have been shown to describe therelationships between the components of the inter-vertebral cage 300,one ordinary skill in the art will recognize that other angles arepossible, and should be viewed as part of this invention. One ofordinary skill in the art will further recognize that the use ofparallel legs 306-309 is conducive to the impaction of the legs 306-309into vertebrae or the insertion of the legs into pre-drilled holes;however, other angles may be utilized to address alternative situations,including the insertion of one leg at a time.

Upon the application of energy, the inter-vertebral cage 300 in adeformed or second shape 328 commences to change from the martensiticstate to the austenitic state. Upon completion of the austenitic phasechange, the inter-vertebral cage 300 has returned to the original orfirst shape 327. Upon cooling, the inter-vertebral cage 300 retains theoriginal or first shape 327. One of ordinary skill in the art willrecognize that upon the transformation of a shape memory alloy to theoriginal shape 327, a force is created, and accordingly, theinter-vertebral cage 300 may be utilized in applications where retainingand residual forces are required.

In this third embodiment, the phase change from the deformed or secondshape 328 to the original or first shape 327 creates forces as shown inFIG. 17B. The bend 335 moves from the angle 370 (angle associated withsecond shape 328) to a more acute angle 360 (acute angle associated withthe first shape 327), thereby rotating the first leg 306 and the thirdleg 308 toward the first engagement plate 302. In a similar fashion, thebend 340 moves from the angle 375 (angle associated with second shape328) to a more acute angle 365(acute angle associated with the firstshape 327), thereby rotating the second leg 307 and the fourth leg 309towards the second engagement plate 303. The bend 336 moves from theangle 371 (angle associated with second shape 328) to a smaller angle361 (associated with the first shape 327). Similarly, the bend 339 movesfrom the angle 374 (angle associated with second shape 328) to a smallerangle 364 (associated with the first shape 327). Additionally, the bend337 moves from angle 372 (substantially perpendicular angle associatedwith second shape 328) to angle 362 (obtuse angle associated with firstshape 327). Similarly, the bend 338 moves from the angle 373(substantially perpendicular angle associated with second shape 328) toangle 363 (obtuse angle associated with first shape 327). Further, thecloseout 305 moves from angle 376 (acute angle associated with secondshape 328) to the angle 366 (larger angle associated with first shape327).

In this third embodiment, compressive forces are created between thefirst engagement surface 345 and the third engagement surface 347.Additionally, compressive forces may be created between the secondengagement surface 346 and the third engagement surface 347 as the firstleg 306 closes down on material disposed between the first leg 306 andthe first engagement plate 302. Compressive forces are also createdbetween the third engagement surface 350 and the first engagementsurface 348, and between the second engagement surface 349 and the thirdengagement surface 350 as the second leg 307 moves towards the secondengagement plate 303. Expansive forces are further created by the firstengagement plate 302 and the second engagement plate 303 as the bends337-338 expand to angles 362 and 363, respectively. When the firstthrough fourth legs 306-309 are secured, a thrust component is createdas the inter-vertebral cage 300 moves from the first shape 327 to thesecond shape 328. The thrust force, shown in FIG. 17B, liesperpendicular to the plane of the spacing member 101 and towards thecloseout 305. The thrust force is created when the legs 306-309 arepinned, and the first and second engagement plates 302 and 303 move awayfrom each other during the shape change.

FIG. 18 provides a flowchart illustrating the method steps associatedwith utilizing the inter-vertebral cage 300 to angularly adjust and fusetwo vertebrae together. The process commences with step 80, wherein asurgeon fixates a first vertebra 380 and a second vertebra 381 at adesired working position. The surgeon continues with step 82, wherein afirst securing location is identified in the first vertebra 380, and asecond securing location is identified in the second vertebra 381 at aspacing complementary to a spacing between the legs 306-309 of theinter-vertebral cage 300. The process continues with step 84, whereinthe surgeon inserts the legs 306-309 into the securing locations, suchthat the first and second engagement plates 302 and 303 are disposedbetween the first and second vertebrae 380 and 381. In step 86, thesurgeon applies energy to the legs 306-309 of the inter-vertebral cage300, thereby securing the inter-vertebral cage 300 to the first andsecond vertebrae 380 and 381. The process continues with step 88,wherein the surgeon applies energy to the body 304 of theinter-vertebral cage 300 to angularly adjust the first vertebra 380relative to the second vertebra 381, and into a desired correctiveposition. Once the first and second vertebrae 380 and 381 are in thedesired corrective position, the surgeon moves to step 90, wherein bonegraft material is inserted into the cavity 314, such that the bone graftmaterial unites with the first and second vertebrae 380 and 381 throughthe first and second apertures 310 and 311. Upon bone fusion, the graftmaterial and the first and second vertebrae 380 and 381 become a singleunit.

FIG. 17 a provides a side view of the inter-vertebral cage 300 in thesecond shape 328, wherein the legs 306-309 are substantially parallel toeach other, and the closeout 305 is angled slightly downward. Uponinsertion of the legs 306 and 308 into the first location on the firstvertebra 380, and the insertion of the legs 307 and 309 into the secondlocation on the second vertebra 381, the body 304 moves between thevertebrae 380 and 381, until the second engagement surfaces 346 and 349contact the respective vertebra 380 or 381. Upon full insertion, thespacing member 301 and the engagement plates 302 and 303 are disposedbetween the vertebrae 380 and 381. In this position, the closeout 305does not contact the second engagement plate 303. Upon the applicationof energy to the legs 306-309, the legs 306-309 move from the secondshape 328 to the first shape 327, thereby drawing the legs 306-309toward the inter-vertebral cage 300, and further securing theinter-vertebral cage 300 to the vertebrae 380 and 381. Upon theapplication of energy to the body 304, the bends 337 and 338 extend tothe first shape 327, thereby drawing the second engagement plate 303away from the first engagement plate 302.

The closeout 305 similarly moves from the second shape 328 to the firstshape 327, thereby extending towards the second engagement plate 303until the closeout 305 contacts the extended engagement plate 303. Atthis point, the cavity 314 is substantially closed out, as shown in FIG.17B. While this embodiment has been shown with bone graft material beinginserted after the application of energy to the body 304 of theinter-vertebral cage 300, one of ordinary skill in the art willrecognize that bone graft material may be inserted into the cavity 314at alternate times, or not at all.

In an extension of the third embodiment, an inter-vertebral cage 390 issimilar in form and function to the inter-vertebral cage 300; however,the inter-vertebral cage 390 does not include an integral closeout, asshown in FIGS. 19A-19C. Accordingly, like parts have been labeled withlike numerals. As shown in FIG. 19A, the inter-vertebral cage 390additionally includes an inner surface 392 disposed on a side of thefirst engagement plate 302 closest to the cavity 314, an inner surface393 disposed on a side of the second engagement plates 302 closest tothe cavity 314, a first retention feature 391 and a second retentionfeature 394 disposed on the inner surfaces 392-393. In this specificexample, the retention features 391 and 394 are raised features that aredisposed on each surface. The second retention feature 394 is disposedat a predetermined distance from the first retention feature 391. Theretention features 391 and 394 are disposed in alignment with theopposing pair, and are located in proximity to the location of theintegral closeout of the previous embodiments. In this fashion, anobject may be retained between the retention features 391 and 394. Whilethis embodiment has been shown with two retention features 391 and 394,one of ordinary skill in the art will recognize that a multitude ofretention features or retention feature designs, included but notlimited to tabs, slots, threads, and grooves, at a predetermined spacingmay be utilized.

As shown in FIG. 19B, the closeout 395 is a separate component and issimilarly constructed from shape memory material. Though one skilled inthe art would recognize that non-shape memory materials could be usedfor the closeout to maintain the separation of the engagement plates 302and 303. Accordingly, the closeout 395 includes a first shape 396 and asecond shape 397. In this specific example, in the first shape 396 thecloseout 395 is planar in shape, and is of a length 398 that iscomplementary to a distance between the retention features 391 and 394disposed on the first engagement plate 302 and the second engagementplate 303. In the second shape 397, the closeout 395 deformed to acurved shape, and a length 399. In this example, the length 399 isshorter than the length 398, and therefore may fit between the highestparts of the retention features 391 and 394.

Use of the inter-vertebral cage 390 is substantially identical to theinter-vertebral cage 300, however, two additional steps are required. Asshown in the method flowchart of FIG. 20, the process commences withstep 80, wherein a first vertebra 380 and a second vertebra 381 arefixated at a desired working position. In step 82, a first securinglocation is identified in the first vertebra 380, and a second securinglocation is identified in the second vertebra 381. The inter-vertebralcage 390 is inserted into the first and second securing locations of thefirst and second vertebrae 380 and 381 utilizing any of the methodspreviously disclosed, step 84. Once inserted, energy is applied to thelegs 306-309 to secure the inter-vertebral cage 390 to the first andsecond vertebrae 380 and 381, step 86. Energy is then applied to thebody 304 of the inter-vertebral cage 390 to reorient the first andsecond vertebrae 380 and 381, step 88. Next, step 90, bone graft isinserted into the cavity 314. The process then requires the insertion ofthe closeout 395 in the second shape 397 between the first and secondretention features 391 and 394, step 92. Energy is then applied to thecloseout 395 to force the closeout 395 to move from the second shape 397to the first shape 396, thereby extending the length 399 of the closeout395 to length 398, step 94. Upon the application of energy to thecloseout 395, the closeout 395 must be guided between the first andsecond retention features 391 and 394. Once extended, the closeout ispermanently installed between the retention features 391 and 394, andthe first and second engagement plates 302 and 303, thereby closing outthe cavity 314, providing load bearing capability between the engagementplates 302 and 303, and aiding in the retention of bone graft materialin the cavity 314. While the method of implanting inter-vertebral cage390 has been presented, one of ordinary skill in the art will recognizethat the sequence of steps may be changed to meet a specific clinicalneed.

While the non-integral closeout 395 has been shown as an extension ofthe third embodiment, one of ordinary skill in the art will recognizethat the use of a non-integral closeout 395 is possible with allembodiments of this invention.

In a fourth embodiment a cage 490 is utilized in an opening wedgeosteotomy to change the angulation of an end portion of a tibia 420. Thecage 490 is similar in form and function to the inter-vertebral cage 390according to the extension of the third embodiment that does not includean integral closeout. Accordingly, like parts have been referenced withlike numerals. As shown in FIG. 21A, the cage 490 includes the innersurface 392 disposed on a side of the first engagement plate 302 closestto the cavity 314, the inner surface 393 disposed on a side of thesecond engagement plate 303 closest to the cavity 314, the firstretention feature 391 and the second retention feature 394 disposed onthe inner surfaces 392-393. In this specific example, the retentionfeatures 391 and 394 are raised features that are disposed on eachsurface. The second retention feature 394 is disposed at a predetermineddistance from the first retention feature 391. The retention features391 and 394 are disposed in alignment with the opposing pair, and arelocated in proximity to the location of the integral closeout of theprevious embodiments. In this fashion, an object may be retained betweenthe retention features 391 and 394. While this embodiment has been shownwith two retention features 391 and 394, one of ordinary skill in theart will recognize that a multitude of retention features or retentionfeature designs, included but not limited to tabs, slots, threads, andgrooves, at a predetermined spacing may be utilized. Further, one ofordinary skill in the art will recognize that if the strength of theshape memory metal or the bone graft placed between the vertebrae, forall embodiments of the spinal cage, or for this fourth embodiment, foruse in an osteotomy is high, a closeout or retention features will notbe needed to resist the functional loading of the bone. The need for acloseout would also be eliminated if the length of the engagement plates302 and 303 were short, or other implants outside the scope of thisinvention were intended for use in the procedure so as to share thefunctional load of the bone.

As shown in FIG. 21B, the closeout 395 is a separate component and issimilarly constructed from shape memory material. Accordingly, thecloseout 395 includes a first shape 396 and a second shape 397. In thisspecific example, in the first shape 396, the closeout 395 is planar inshape, and is of a length 398 that is complementary to a distancebetween the retention features 391 and 394 disposed on the firstengagement plate 302 and the second engagement plate 303. In the secondshape 397, the closeout 395 is deformed to a curved shape, and a length399. In this example, the length 399 is shorter than the length 398, andtherefore may fit between the highest parts of the retention features391 and 394.

As shown if FIG. 21A, the tibia 420 includes a tubular portion 422connected to a knuckle portion 421. The knuckle portion 421 is severedat an adjustment plane 424, up to the point where only a small segmentremains connected on the opposite end of the knuckle portion 421,thereby creating a first bone 426 and a second bone 427. The first bone426 includes a bone working face 431 and the second bone 427 includes anend portion adjusting face 432 disposed on the partially connectedsecond bone 427. The partially connected second bone 427 hinges about aconnection point 429, and is rotated away from the adjustment plane 424,such that the cage 490 may be impacted or inserted into a positionbetween the first bone 426 and the second bone 427. Installation andoperation of the cage 490 is substantially identical to the installationand operation of the cage 390, however, additional steps may be requiredin the current application. Illustratively, in this embodiment, the legs306-307 of the cage 490 are impacted into the partially connected secondbone 427 and the knuckle portion 421 of the first bone 426, such thatthe body 304 is disposed between the end portion adjusting face 432 andthe bone working face 431. Upon the application of activation energy,the legs 306-307 of the cage 490 move toward their respective engagementplates 302 or 303 to secure the cage 490 to the first and second bones426-427. Upon the application of activation energy to the body 304, theengagement plates 302-303 move toward each other to align the endportion adjusting face 432 with a desired corrective plane 428. Afterthe desired position has been reached, the closeout 395 is insertedbetween the retention features 391 and 394, and energized, such that thecloseout 395 supports the cage 490 in the vertical direction.

Use of the cage 490 is substantially identical to the inter-vertebralcage 390, however additional steps are required in the tibial endportion adjustment operation. As shown in the method flowchart of FIG.22, the process commences with step 470, wherein a surgeon fixates thefirst bone 426 at a desired working position. The process continues withthe severing of the first bone 426 at an adjustment plane 424, such thatonly a small portion remains connected to the first bone 426, therebyforming a partially connected second bone 427, step 471. In step 472,the surgeon fixates the partially connected second bone 427 and thefirst bone 426 at a desired working position. In step 473, the surgeonidentifies a first location in the first bone 426 and a second locationin the partially connected second bone 427, at a spacing complementaryto a leg spacing of the cage 490. The cage 490 is inserted into thefirst and second securing locations of the first bone 426 and the secondbone 427 utilizing any of the methods previously disclosed, step 474.Once inserted, energy is applied to the legs 306-309 to secure the cage490 to the first bone 426 and the partially connected second bone 427,step 475. Energy is then applied to the body 304 of the cage 490 toreorient the partially connected second bone 427 relative to the firstbone 426, step 476. Next, in step 477, bone graft material 430 isinserted into the cavity 314 of the cage 490 and between the boneworking face 431 and the end portion adjusting face 432 to promote bonefusion.

The process then requires the insertion of the closeout 395 in thesecond shape 397 between the first and second retention features 391 and394, step 478. Energy is then applied to the closeout 395 to force thecloseout 395 to move from the second shape 397 to the first shape 396,thereby extending the length 399 of the closeout 395 to the length 398,step 479. Upon the application of energy to the closeout 395, thecloseout 395 must be guided between the first and second retentionfeatures 391 and 394. Once extended, the closeout 395 is permanentlyinstalled between the retention features 391 and 394, and the first andsecond engagement plates 302 and 303, thereby closing out the cavity314, providing load bearing capability between the engagement plates 302and 303, and aiding in the retention of bone graft material in thecavity 314.

While this embodiment has been shown with a partial cut through theknuckle portion 421 of a tibia 420, one of ordinary skill in the artwill recognize that the methods described in this fourth embodiment maybe applicable to fully severed bones, partially severed bones, or thelike. One of ordinary skill in the art will further recognize that cage490 and its methods may be applicable to bones other than tibia bones,and that the sizes, lengths, displacements, and angles of the cage orcage components may be adjusted for use in specific applications, asdescribed in the embodiments of this disclosure.

One of ordinary skill in the art will further recognize the preferredembodiment and each alternate embodiment could accomplish the samefunction and have the same design features through apertures 110 and 111that are holes, slots, grooves, an irregular opening or an open meshstructure.

Additionally, one of ordinary skill in the art will further recognizethat the spacing member 101 planar section 109 of the preferredembodiment and all similar design features of each alternate embodimentcould be located not on the first ends 118 and 121 but between theengagement plates 102 and 103 at a number of different locations alongits inner face 500 or periphery 502, as shown in FIG. 23A-G. At thislocation the spacing member 501, allows a number of designs for theshape changing members that distract, contract or change the angle ofthe first and second bones. Finally, this skill in the art wouldunderstand that the expansion or contraction nature of the planarsection 109 in each of the embodiments could be achieved not by having acurved section that straightened but by having a planar section that wascut into several members spanning the engagement plates 102 to 103 wherethese members were “S” 503, “Z” 504 or interlaced 505 or 506 so that inthe first shape they were straight and in the second shape they returnedto their contracted “S”, “Z” or interlaced shape so as to contractspacing member 501 or alternatively they are straight in the first shapeand “S”, “Z” or interlaced in their second shape so as to straighten tocause expansion of the cage and separation of bone. The expansion andcontraction members can be selected from the family of shapes thatinclude but are not limited to “S”, “Z”, “C”; “O” 508 or “C” 507 shaped.

Although the present invention has been described in terms of theforegoing preferred embodiment, such description has been for exemplarypurposes only and, as will be apparent to those of ordinary skill in theart in light of the multiple alternate embodiments that manyalternatives, equivalents, and variations of varying degrees will fallwithin the scope of the present invention. That scope, accordingly, isnot to be limited in any respect by the foregoing detailed description;rather, it is defined only by the claims that follow.

1. A cage, comprising: (a) a body adapted for insertion into a spacebetween a first bone and a second bone, wherein: (i) the body comprisesa first engagement plate, a second engagement plate, and a spacingmember coupling the first engagement plate with the second engagementplate, (ii) the space has a boundary comprising a first portion of thesurface of the first bone and a first portion of the surface of thesecond bone, and (iii) the first engagement plate is operable to facethe first portion of the surface of the first bone while the secondengagement plate faces the first portion of the surface of the secondbone; (b) a first leg secured to the body and adapted to engage thefirst bone at a second portion of the surface of the first bone, whereinthe second portion of the surface of the first bone is exterior to thespace; and (c) a second leg secured to the body and adapted to engagethe second bone at a second portion of the surface of the second bone,wherein the second portion of the surface of the second bone is exteriorto the space.
 2. The cage according to claim 1, wherein the bodycomprises shape memory material and is operable to transition to an enduse shape upon the application of energy thereto.
 3. The cage accordingto claim 2, wherein the body is operable to deform so as to change therelative position of a first bone and a second bone.
 4. The cageaccording to claim 2, wherein the first leg is operable to deform so asto move, engage and provide fixation in the first bone.
 5. (canceled) 6.The cage according to claim 2, wherein the first leg is secured to thefirst engagement plate and the second leg is secured to the secondengagement plate.
 7. The cage according to claim 3, wherein the body isoperable to distract the first bone and the second bone to a desiredcorrective position.
 8. The cage according to claim 2, wherein, upon thebody, the first engagement plate and the second engagement plate areoperable to contract toward each other.
 9. The cage according to claim2, wherein the body in the end use shape operatively adjusts an angularrelationship between the first bone and second bone.
 10. The cageaccording to claim 1, wherein the space comprises the disk space betweenadjacent vertebrae.
 11. The cage according to claim 10, wherein the bodyis load bearing.
 12. The cage according to claim 8, wherein thecontraction of the first engagement plate and the second engagementplate is operable to create compressive forces (a) between the firstengagement plate and the first leg and (b) the second engagement plateand the second leg.
 13. The cage according to claim 8, wherein themovement of the first engagement plate and the second engagement plateaway from each other is operable to create a thrust force when the firstleg and the second leg are secured.
 14. The cage according to claim 2,further comprising: a closeout comprised of shape memory materialdisposed on the first engagement plate, wherein, upon the application ofenergy to the body, the closeout extends and contacts the secondengagement plate, thereby closing out and retaining bone graft materialin a cavity disposed between the first and second engagement plates. 15.The cage according to claim 14, wherein the closeout is load bearing.16. The cage according to claim 2, wherein the first leg and the secondleg comprise shape memory material and are adapted to transition to anend use shape upon the application of energy thereto.
 17. The cageaccording to claim 16, wherein, upon the application of energy thereto,the first leg moves toward the first engagement plate and the second legmoves toward the second engagement plate.
 18. The cage according toclaim 17, wherein the contraction of the first leg and the second leg isoperable to create creates compressive forces (a) between the first legand the first engagement plate, and (b) between the second leg and thesecond engagement plate.
 19. The cage according to claim 2, wherein thespacing member includes an extension section, and further wherein, uponthe application of energy, the extension section is operable to increasethe width of the spacing member.
 20. The cage according to claim 19,wherein the extension of the spacing member is operable to createdistraction forces (a) between the first engagement plate and the firstbone and (b) between the second engagement plate and the second bone.21-26. (canceled)
 27. The cage according to claim 1, wherein the firstleg and the second leg comprise shape memory material and are adapted totransition to a shape including an end use shape upon the application ofenergy thereto.
 28. The cage according to claim 27, wherein, upon theapplication of energy thereto, the first leg moves toward a firstengagement plate and the second leg moves toward a second engagementplate.
 29. The cage according to claim 28, wherein the contraction ofthe first leg and the second leg is operable to create (a) compressiveforces between the first leg and the first engagement plate, and (b)compressive forces between the second leg and the second engagementplate. 30-33. (canceled)
 34. A method of reorienting a first bone andsecond bone, comprising: a. providing an inter-vertebral cage comprisingi. a body adapted for insertion into a space between the first bone andthe second bone, wherein the the body comprises a first engagementplate, a second engagement plate, and a spacing member coupling thefirst engagement plate with the second engagement plate, ii. a first legsecured to the body, and iii. a second leg secured to the body; b.fixating the first bone and a the second bone in a desired workingposition; c. inserting the body into the space, wherein i. the space hasa boundary comprising a first portion of the surface of the first boneand a first portion of the surface of the second bone, ii. the firstengagement plate faces the first portion of the surface of the firstbone, and iii. the second engagement plate faces the first portion ofthe surface of the second bone, and d. inserting the first leg into thefirst bone and the second leg into the second bone such that the bodyresides between the first bone and the second bone, wherein (i) thefirst leg is inserted into the first bone at a second portion of thesurface of the first bone, (ii) the second portion of the surface of thefirst bone is exterior to the space, (iii) the second leg is insertedinto the second bone at a second portion of the surface of the secondbone, and (iv) the second portion of the surface of the second bone isexterior to the space.
 35. The method according to claim 34, wherein thebody, first leg, and the second leg comprise shape memory material andare adapted to transition to an end use shape upon the application ofenergy thereto.
 36. The method according to claim 35, furthercomprising: e. applying energy to the first leg and the second leg,thereby forcing the first leg and second leg to move from the secondshape to an end use shape, wherein the end use shape contracts (i) thefirst leg toward the first engagement plate to secure the cage to thefirst bone, and (ii) the second leg toward the second engagement plateto secure the cage to the second bones, and f. applying energy to thecage, thereby transitioning the cage to the end use shape, wherein theend use shape moves the first bone and the second bone into a desiredcorrective position.
 37. The method of reorienting a first and secondbone according to claim 36, further comprising: g. inserting bone graftmaterial into a cavity of the cage to aid in fusing the first bone andthe second bone together.
 38. The method of reorienting a first andsecond bone according to claim 35, further comprising: e. applyingenergy to the first leg and the second leg, thereby forcing the firstleg and second leg to move from the second shape to an end use shape,wherein the end use shape contracts (i) the first leg toward the firstengagement plate to secure the cage to the first bone, and (ii) thesecond leg toward the second engagement plate to secure the cage to thesecond bones, and f. applying energy to the body of the cage to reorientthe first bone and the second bone and further distract the first boneand the second bone. 39-40. (canceled)
 41. The method of reorienting afirst and second bone according to claim 35, further comprising: e.applying energy to the first leg and the second leg, thereby forcing thefirst leg and second leg to move from the second shape to an end useshape, wherein the end use shape contracts (i) the first leg toward thefirst engagement plate to secure the cage to the first bone, and (ii)the second leg toward the second engagement plate to secure the cage tothe second bones, and f. applying energy to the body of the cage,thereby forcing the body to move from the second shape to the end useshape, wherein the end use shape contracts the first bone and the secondbone, and restrains the first bone and the second bone in the contractedposition. 42-53. (canceled)
 54. The cage according to claim 1, whereinthe space comprises the joint space between adjacent bones.
 55. The cageaccording to claim 54, wherein the body is load bearing.
 56. The cageaccording to claim 1, wherein the space comprises a cut or fracturebetween adjacent segments of a bone.
 57. The cage according to claim 56,wherein the body is load bearing.